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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c014d9cca21337d11c0eceb63c6ad73705228bdc579d3ee20c797daf99f2ca8' 
  AND token = 'zd0kBHhIN0U+8Fgt6LwZnmd8h0ZnTz2hUnzBJVLVARc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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