SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb3b2f877c62322ad8408daecdc6b6955cc7e30a62e83be4bf64968145f5f877' 
  AND token = 'G4iMkRnG6Sn1G/x+AjlenrlOGHWUtdF4Ucpa0yv7jPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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