SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6df6d1c850644c0048347af356d8ecfaa3e2a95bf3058383861939be7bf21539' 
  AND token = 'JkqVdSvC/fKK+QSNVmu+H7BxgfEHO5Q4X7dDPh4AlzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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