SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6682443bc19050f301cc68d2a186194cff297b9d8e75d30ce22665d4defd55f1' 
  AND token = 'UPbH+IscJZSvYIrDzIaGfkJD/ybzS5qD7IOVgd5p/L0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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