SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b18a042ecd50cfd90ade9a2487991776f9ffc6313648216e52d13a530fdf66a' 
  AND token = 'rEIWOy1Vb/DQrnDiPRxSwx91htich6RoxM4y5CpXir0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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