SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5ceffcc6f12e4be383aed62cc1650bc10074a37bcc13e0b4738a35e65934f6a' 
  AND token = 'WHBTQzDgg9h1mPHSKwuZDR7SNS8NPs3kwf2rdywm6FI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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