SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a2e34be620aee0870873f69bf2d323107074195cb27b3318d5372937c2a620' 
  AND token = 'hr2Gezd9PLXpDTb1KgECGDnnFwgRpR8XkZkX6Ibn9qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}