SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '81ea79716f6c1c2bac7199db2378a4e452739db9243c027fd2bbc18c14cf6f0a' 
  AND token = '5cXem/WeDiffd+q4Yr/0GztMCYH/BWOhM3ySuQbzzLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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