SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4112a21f79372dab926c4ea22c870e6f1a5b29597642e360dad3dd6fe20449ad' 
  AND token = '3Ej8imkzBQsPUHpnSJINtOOMEiBhuxLPWvIt0/oySwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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