SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e8b92bf870484da91eb35d46cd916a0236769b353c891d00af73290ef12938b' 
  AND token = '32/nUkVd/NqbLqCpFDT5U2EvashuH9VJnWiZgtPO8vA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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