SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a81d9840b421dff72af66dc754b79d7646044b273ffa5837235438573105f8d' 
  AND token = 'Yfg99ky8zAXjMarSMFBD0e17lwOhCIJg80kSx59k+Co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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