SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb34511a81478cdc443b7a895fbd0dee65797e659c692a0c1834f4d7ac856d76' 
  AND token = '3RTnbL3Eozpoaiysnu2VNlr/CRaOlVhCgVs56B+0vME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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