SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b863ee622deb4bd0e64167897a76d13c2a01376d19900b5c45fc13e86ad8108e' 
  AND token = 'eOvRVzf2Ttx36WTc33uOLMgitw7Kb0yJgBiDAQ8ldjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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