SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b57963ba91be2f343cb606ca57c8a9c977ba9925874047499f144fdda58e0336' 
  AND token = 'pnluTL1PuVOrnCErDgNbWIGzcMGzvxILrOwetGiNrhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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