SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518e8f0d3ff7ce47258c8a2aef6bf839a61c95edd455595e5fe85c2c527d1143' 
  AND token = 'QMLAcUyWEHTWQwlfqtkJpHCEgBr/LQDSUNzXb6xFOPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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