SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b1dee1758c6c0808f740d836736ab376859a527d3905e4c6d107f8f31fc3553' 
  AND token = 'puRJdLh7nDK1Ja2WHQBEojtfE8fQEBFKteiVhP/MH4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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