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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f1c20a0540be4dd4617f02ea7ff6a962f0ecbaa2bdfe9f1b1e164f5b5c8e08f' 
  AND token = 'Xzr0xPcLs5scli+ZxiQE+1WHClmdKVH5VwPM0p+X+5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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