SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8990199e4257cbe0b180f856f0ff4a53bd95e14517e2649e979013ead796bf87' 
  AND token = 'mpnntOhlab3bPo4+3N/ToK+gmBXqGkBj9KpY/8Z2n30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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