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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b232d9a8ca96f26fceaf4a40d179d9a6c1bb1c76c2d61b0a7ac647fe60926723' 
  AND token = 'xCj+MTUPMuMbc92uaa+OfCMo/WsmVFK/KMqOeWfsiwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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