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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7286d66d3fb86cb107ec94f7e773cbca2b112bf1c3ea37c736e0e80a32ac229' 
  AND token = 'l+5IZBTTCO6+SO0p1RsH5EYQIHwAwzZ41mMCdYAMhr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}