SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c0f234cfadf75181833e55a42c1507b0ebef7ab582784b6d2155ee0a32d108c' 
  AND token = 'MV/FMxuTQJIHGjt0zNuyC+Ujtb+MFbW/UqYW46h62OU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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