SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3d0f20164515ffc6681b6822cc5ceec6dfbaf8a1058f1db8f337dd6e879435e' 
  AND token = '/++FIlw9NftKKj0zBRA+yahwFzGLSJGPftTgVPVFmjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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