SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a94ff4e7055cf0ef37f523c0736f6ed2ebab75819bd545d916730216f543326c' 
  AND token = 'Ru18lnVYeWlsMo8aGD57vDVatQvT9QuFM3UDm6zDhKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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