SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '892d3dc8993119d5b7392731a3f52bc930fac67a43abacec67cb9d247f1fa486' 
  AND token = '+vMhs9sCQ8N/uP3CzDXyepzHdA/CNBL8Lq16HZtGGfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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