SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '645bb8e3ad3ab5bed84a7921158a25c84349103a07d2a293bb6501b28eadf77d' 
  AND token = 'vz+Y/wq5yyesk9eZ0Lb6OGSvfGxcMN4q4Ph0qqtWNBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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