SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96ab38b836f8a17ab5e00d344dbf820c56fba488d459a0d78b5b88aa102e6ef1' 
  AND token = 'eiuSvv/lK/nDk3rDlyDcvmNC4Z/BSiDiXhxSZGfD0JQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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