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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dc66b2baa9e06dbca20e4c27b89ace1cd5fe0e2d92618e5bca9d51e7ea8c170' 
  AND token = 'BiDmaPE9ZlXZyebvohjNoGExAZVVT/hDgfaje+XJbBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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