SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c1c9657bd767ca200e94884e7dbcc35d1f56f953884497cea79cb3e1bd88c74' 
  AND token = 'zTSy+jkLPfF44eRR71E7/znNS/ntuoN4OH3WoLcgvqc=' 
  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"
    }
  }
}