SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '623b26e18e724f16fe3a13a4cbc86340af59fb2bae4bca472790c9a214e10c5a' 
  AND token = 'nMjzHRgTmNG/C5JzWKmGFpi5hYkGUtrMIjdAgyhcvc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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