SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4717ce000a4ebb9a9668806f2e6c54f5138aa5f2ad3317569de52733b3e640da' 
  AND token = 'CunyzVy+dt2UegTIsBXP4DopjZQPQ2LB5p7XSVDZqPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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