SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb9822dfaf25b12abd3d089deeb1d73a86bc2d9e62cad9437afe4644644d17c2' 
  AND token = 'MeeAIfZEDFw5GQcYPh12nQHy+bn3DyT1ULLvdRdieO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}