SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c9bd028ae9b89a842e6182e02642257fbf2d44edf184d070599921a8bb4365e' 
  AND token = '6iSuExPssrvyOF2yblz+kQlYrYrE8Wb3Uey9E+0RHUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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