SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20c127bd4476a28658016a782998033c89298516b40860daf216f5ae5972a726' 
  AND token = 'zj/zUNjAswNviRXDtQNFSmMgu42v2zMo/Sb/ucC6OiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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