SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec61de0d45efdfbc44496953ff50dc49158b18d3e863294ce1015ea91f433ca8' 
  AND token = 'mEzUTCQ1FIZGnT3lBgAIRPC80R1ohRw7+SLk/3dtLHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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