SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a6c150c64bd0f88f7a340fc6cdec36a1480a4c43a8453703d79240eb305217f' 
  AND token = '3VTFEBFlgfVG4+Uq9ekONWRczky0ENVmYJXF6/Nn6UE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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