SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bca7dc250609abb17a0714e79c60b31ca756b7ede47ba7964250805b007bab3f' 
  AND token = 'fP3K/YgKiy/BQmQNC6qsHkzcmc/aPVQLhGqydlM2PB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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