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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ef0e18f1e1b19226ea6795722edea08a7902268e5be35fd57af494516a1d838' 
  AND token = '0jKilppdvjxEOZWgIDmZRgFGeuAofxdR7kxhYa0TdPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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