SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6534d28862abebbfd1e0c5112a2de39c243c73113309482dd17266f575483931' 
  AND token = 'cK3OElGKbJTJq2xjXdioiPmXTagRTspA/a3fVAJSWqc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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