SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c50db3d81f0a3fac729497fe6201af5e932711cc4f0a22b9e5d77c927d155067' 
  AND token = 'pVDRb73RcyEbvs5aMrUymhKSZI+rqvEMkEMakbUH5FA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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