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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473186e8d73fbf294307091b0dd0983050282204ff3f3d509d71bd9341deadf0' 
  AND token = '5iE52zfQ6VRKPBEzaegD328b1xvl2NNQFh4NTMSJmGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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