SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57a4332da3c2f051bf10637903baf222d1ce0d25a707c8999f1cbb2bdc335c05' 
  AND token = 'E2g+dBQMLJV6E7eGQMAmfnGaPGhY4GzEO/mFupjCw0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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