SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5d0dba2ea3570ecbd3089199c03ddff63d29743b12cb8e726ec6f6567277c4a' 
  AND token = 'p/Krz3ycXLtG4H6PoNPXJXmhLDLQeuwztoKrR+ggQHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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