SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7500828d1db1d701772b0f7769778177508234028cad6bfd46cb932cf8996de6' 
  AND token = 'fqUPhIUV3cHzrPOtvfFMuFJV0FhZlSoOFEFHT9mqGJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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