SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50ee914a498af94eb12d1b6bd098041bdf26fc41105f05a47f3a665567036f8' 
  AND token = 'W0/uMd28F9aFYq6BaQwA3+0c2NTh/ijrYR5aHZ7iE7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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