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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e9d369bbeb847c8a0e10b181fa9b1929401e7e52473566aa65713f6f1ca34c8' 
  AND token = 'O2LFv+tudScLTqbRvOr5SQdT0qQHBn8AM4Yix9rzmdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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