SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02702f272865deca807ea15b80764e02bed88ef2eb1047dd93f3da6c98b6187c' 
  AND token = '3RB6sBjCja87BeCv+LsHbvsry35flhCTr8YN3XETLl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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