SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc71cb02781d7acdfdecf4abc9e41eeea8c37890942c03960706e22d4fe07f50' 
  AND token = 'nSkp46JR8HlRMOCOWZkFHE1jIn8+DtO1Rg3JGZgkkAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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