SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d4f43898d70332228c16aecc816d56b991df7db9da27f889d86969824b311b9' 
  AND token = '1d0COYRaFXY7W0F6tZtQfeBIrdDw39XNXhpCCmwdAgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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