SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73f09e195bacd80fa611daffc834bae28580721805aefaf4b27dd89aa68909ec' 
  AND token = 'gRD+uc0wO5ddetTyInfdfgZ8NIfdA2ncBbqS4WrMBb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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