SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f34151e45f714ce5d773c5c9e5c5519f96ef005d009a45aef8129310a9abd66' 
  AND token = 'PWyqfEA9cVHTR5lGA8lRaetgJnpCKojdp8DkZg5/gyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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