SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc6a283068b9a6fb8eb629a765ac90197f28dbee10507c04c8872d8ecf650c76' 
  AND token = 'c5zORto2uayQKiEsf7xB6WR0Q3/jzNvlKyohuOf9740=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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