SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b14eba10dcdd6f02729fc72fafb7f2feaf5f7fec85b58fdae600903d2863263b' 
  AND token = '27BBOXGYeICpwT4jGfVWce3CIVJoLWChW6uoSlITDaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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