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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8d71b32fadf00d63c4a39b2fb96791fb06050deb2371f0efda1e9d0a19b45b2' 
  AND token = 'ec3n/nxwkLy1IHx89HFCN9Vcvs+BIZvaw4+1NLalGKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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